Phonograph sound box



June 3, 1924. 1,496,313

J. HOFFAY PHONOGRAPH SOUND BOX Original Filed July 1918 2 Sheets-Sheet 1 sevk Hen-HA1 Wan/TM jume 3 1924.

1,496,313 I J. HOFFAY PHONOGRAPH SOUND BOX Original Filed July 2, 1918 2 Sheets eel Patented June 3, i924,

TATES JOSEPH HOFFAY, OF NEW YORK, N. Y.

PHONOGRATLH SOUND BOX.

Application filed July 2, 1918, Serial No. 242,988. Renewed October 15, 1923.

phonographs, gramophones and the like, and

more particularly to the means for mounting the stylus lever, or carrier, on the sound box whereby the sound reproduction is greatly improved. a

The present application is an improve ment on the devices, disclosed in my applications Serial No. 10,698 filed'February 25, 1915; and Serial No. 108,346 filed Julylll, 1916. 1

In application No. 10,698, I have 'shown'a stylus carrier freely mounted on the sound box and held to its hearing by resilient means, the resilient means being itself freely held so as to permit the stylus to readily follow the record groove.

In application No. 108,3e6 l have also shown the stylus carrier freely mounted, and in that case I arrange a single resilient means so that it may hold the stylus carrier to its bearing and also act to flex the diaphragm to put it normally under a stress.

In the present invention I preserve the free mounting of the stylus carrier disclosed in my prior cases, and hold it to its bearing by resilient means, which means are freely supported. j

An important feature of my invention resides in the fact that I apply'yielding forces to the diaphragm, said forces acting in opposite directions so that vthe diaphragm is not only quickly responsive to movement but also quickly returns to its normal state when displaced therefrom.

I may also give one or both of the op-,

posed forces the additional function of holding the stylus carrier to its bearing. To accomplish this in the preferred form of my invention, I use relatively long rods or wires and mount them so that they engage the stylus carrier on the opposite sides of its fulcrum. In this preferred form these rods extend. substantially parallel to each other and are flexed tdwards the center of the sound box. This flexure, in a direction parallel to the plane of the sound box serves both to hold the stylus carrier to its bearing,

and to tend to rock it in the opposite direc tions. 1 may also hold the resilient rods flexed by the means which freely engage their ends. 7 I

In the other forms of my invention herein disclosed, the ends of these rods may lie in the same vertical plane'with each other and with the diaphragm. in such forms of my invention the points ofengagement of the retaining means for the rods may also bein substantial alignment with the fulcrum of thestylus carrier, so that said rods form, in effect, an axis about which the stylus carrier may rock during its vibrations.

Another feature of my invention relates to the manner of forming thebearing'for the stylus carrier. Said carrier has a shank portion preferably of substantially cylindrical form, the flat surface or curved edges of one of the/heads of which engages a bearing notch in the sound box casing.

Another feature of my invention relates to the complete insulation of the diaphragm from any sound vibrations not cominuui-' cated through the stylus by the record. I

Other features and advantages will hereinafter appear; The invention is fully illustrated in the accompanying drawings in which Figure 1 is a front elevation ofone form of my improved stylus mounting Figure 2 is a front elevation of a form of mounting in which the stylus lever is forked;

Figure 3 is still another form, and differs from that shown in Figure 2 in'the manner of mounting the resilient rods orwires;

Figure 4 is a side elevation of Figure Figure 5 is a side elevation of Figure Figure 6 is a broken side elevation of I ure 3;

Figure 7 is a bottom plan view of Figure Figure 8 is a bottom plan view of Figure 1 and Figure 9 is a bottom plan viewof Figure Figure 10 is a front elevation of still another and preferred form of my invention;

Figure 11 is a part sectional and part side elevation thereof, showing the manner of mounting the stylus carrier and showing the manner in which the rods 7 and 8 pass through said carrier;

I Figure 12 is a side elevation showing more particularly the manner of securing the ends of the rods by means of screws carried in the brackets carried by the casing;

Figure 13 is a bottom plan view, showing the substantial parallel arrangement of the rods 7 and 8;

Figure 14 is a detailed View showing the manner of engagement of the flat surface 15 of the stylus carrier with the notch in the sound box casing; and

Figure 15 is a detailed View in perspective of the forked stylus carrier.

Referring to the drawings and particularly to Figures 1, a and 8, the sound box 1, which may be of any known or approved construction, carries the diaphragm 2, properly mounted therein. Secured to the diaphragm at 8, is the lever arm .4 forming part of the stylus carrier 5, which carrier has a knife edge 6, engaging a notch cut into the casing of the sound box. This knife edge where it bridges the notch, forms in effect, a continuation of the circular periphery of the sound box, andv has a bearing at two points in the notch.

To: the end that the diaphragm may quickly respond to movements transmitted to it from the sound groove through the stylus carrier, I so mount the carrier that the diaphragm is held by yielding forces which act in opposite directions. These forces are applied meansof rods or wires 7 and 8, lying in a direction generally approximatingthe plane of the diaphragm and which are relatively long and sufficiently stiff to quickly return the diaphragm to normal position. The rods 7 and 8 engage the stylus carrier near its fulcrum and on opposite sides of a plane passing through said fulcrum, the force being applied at opposite sides of said-plane. The said rods may have their ends held in brackets 9 and 10.

These brackets extend from the sound box, each in a radial direction, and are located at substantially equal distances from the notch in the casing, as clearly shown in Figure 8. The ends of these rods are not held fast in the brackets but said ends, on the contrary, are freely held by pins underwhich the rods pass and where they engage the pins are provided with sound insulating material. At or near the middle point of the rod 7, said rod engages the stylus carrier beneath the shoulder formed by the lever arm 4 (Figure 4), and the point of engagement is on one side of the fulcrum of the carrier. Therefore, when the rod 7 is flexed by bringing its ends to the right and under the pins (Figure 8), said rod will tend to rock the carrier on its pivot in an anticlockwise direction, as viewed in Figure 4. The rod 8 may be mounted in a similar manner but so as to tend to rock the stylus in a clockwise direction and therefore oppose the action of the rod 7, and the rocking tendency of the rods 7 and 8 may be substantially equal.

In general, however, it is desirable that the diaphragm be normally held flexed, and it is preferable that the flexure he towards the stronger side of the sound box, that is, towards the left side as viewed in Figure 4. To accomplish this result, the leverage of the rod 7 may be greater than that of the rod 8, or the rod 7 may be flexed to a greater extent by having its ends secured underneath the ends of the rod 8, so that the rocking tendency of the rod 8 is overcome by the rocking tendency of the rod 7, and thus the diaphragm is held normally flexed towards the left. As shown in Fig. 4:, the leverage of the'rod 8 is also reduced by reason of the factthat it engages a notch 11 in the stylus carrier.

This state of normal flexure of the diaphragm, while desirable, is not necessary, and I desire it to be understood that my invention is not thus limited, but is broad enough to embrace a structure in which the forces exerted to rock the stylus carrier are in substantial balance.

When it is desired tohave the diaphragm normally flexed, such fiexure is also readily obtained in assembling the parts by placing In the form of device shown in Figures 2.

5 and 9, the rod 8 passes through a hole 13 in the stylus carrier, which carrier is forked, the two arms of the forks engaging the diaphragm on opposite sides. The hole 13 is in the same vertical plane with the knife edge and very near said edge. In this form too, the knife edge engages the bearing on the sound box to one side of the plane of the diaphragm, and is also displaced slightly to the right of the line joining the center of the brackets 9 and 10, as seen in Figure 9. The rod 8 thus tends to rock the stylus lever in a clockwise direction as viewed in Figure 5. The rod 7 is mounted in the same manner as in the form of device disclosed in Fig. 4, and may overcome the rocking tendency of the rod 8.

The construction shown in Figures 3, 6 and 7 resembles the construction of Figures 2, 5 and 9, in providing a forked stylus lever. The mounting of the rod 8 however is different, as will be seen from Figures 6 and 7. In this form the leverage of the rods is the same, but due to the fact that the rod 7 is flexed more by being passed under the rod 8, the rocking force exerted is greater.

In the several forms described, it will be noted that the rods have their ends secured substantially in the plane of the knife edge, and also that the ends of the rods and the knife edge'are in substantially a straight line. The method of securing the rods permits rocking movements thereof and also longitudinal movement.

In order to provide for a more perfect insulation of the diaphragm from any sound vibrations other than those produced by the record, I not only interpose sound insulating material between the ends of the. resilient rods 7 and 8 and the pins holding said ends in position, but I also interpose insulating material 14 between each rod or wire and the stylus carrier at the point of engagement with said carrier. To accomplish this in the construction shown in Figure 5, where the wire 7 passes through a hole in the stylus carrier, I make said hole large enough to accommodate the wire and also the insulating material. In the other forms, such insulating material is merely placed between the rod and the stylus carrier where they contact.

While all of the several forms of the invention o far described give excellent results in practice, I prefer that form in which the stylus carrier is forked and more particularly that form shown in Figures 10 and 15 inclusive. The form of invention disclosed in these figures differs from the forms previously described in that the stylus carrier instead of having a knife edge, has a flat cylindrical surface 15 for engagement with the walls of the notch in the sound box casing. This form of mounting for the stylus carrier gives two points of bearing surface in the notch and enables the rods 7 and 8 to be so placed that they are substantially in the plane of the surface 15. Thus giving a more solid mounting, with consequently better tone reproduction.

In this form of my invention, I pass the rods 7 and 8 through the lever arms of the stylus carrier and preferably the opening through which the rods pass is of such a size that they fit tightly in the said arms. 'As will be seen from Figure 13, the ends of the rods 7 and 8 instead of being brought together to a substantial central position, have their ends placed apart so that the rods lie substantially parallel. This form of mounting prevents any twisting of the stylus carrier due to the friction caused by the walls of the sound groove against the stylus.

In the form of device shown in Figures 10 and 15 inclusive and also in the form shown in Figures 5 to 9 inclusive where a forked stylus carrier is used, the two arms of the carrier pass to opposite sides of the diaphragm and are suitably connected thereto in such a manner that the joint is airtight. The fork 4:, Figures 5 and 13, passes through an opening in the casing as shown in Figures 7 9 and 13, and said opening must be large enough to give sufficient play to the fork to permit the stylus carrier to vibrate in accord ance with sound record. At the sametime it is very objectionable to permit any opening from the sound box to the outside air; in other words, the air vibrations originating in the sound box should be transmitted to the outside air only through a horn or other suitable sound conveyor- To seal the opening in the sound box, therefore, and at the same time, permit the arm to freely vibrate under the action of the stylus carrier, I have introduced a'viscous substance filling the air space between the arm and the sound box. substance may be of any suitable character, such, for instance, as Vaseline.

What I claim as new is 1. A phonograph sound box comprising a casing, a diaphragm therein, a stylus carrier in operative connection with said diaphragm, a rod in operative connection with said carrier, a second rod also in operative connection with said carrier, brackets on said casing adjacent the ends of said rods, and means in said brackets for maintaining one of said rods in flexed condition for hold This ing said carrier against said casing and for flexing said rod in another direction to rock said carrier to fiex said diaphragm, said maintaining means also holding said second rod flexed to rock said carrier to flex said diaphragm in a direction opposite to that of said first mentioned rod.

2. In a phonographic sound box, the combination with a casing and a diaphragm therein, of a stylus carrier having an operative connection with said diaphragm and having a bearing upon said casing, means for maintaining said carrier upon said casing, comprising a single member tensioned in one direction with respect to said casing to hold said carrier upon its bearing and in another direction to rock said carrier uponits bearing to depress the diaphragm, and a second member engaging said carrier and opposing the tendency of the first-mentioned member to depress the diaphragm, both of said members having bearings substantially in the axis of oscillation of said carrier.

3. In a phonographic sound box, the combination with a casing and a diaphragm therein, of a stylus carrier mounted on the casing, said carrier having forked arms by which it is connected to the diaphragm, one arm extending to one side of the diaphragm and the other arm extending to the other side thereof, and yielding means engaging said carrier adjacent said arms to oppose yielding forces to said diaphragm to thereby maintain the same in normal position.

4. In a phonographic sound box, the combination of a casing having a notch or depression in the periphery thereof, a diaphragm in said casing, and a stylus carrier operatively connected to said diaphragm. and having aflat surface for engagement with the walls of said notch.

5. In a phonographic sound box, the combination of a casing having a notch or depression in the periphery thereof, a diaphragm in said casing, and a stylus carrier having :1 flat surface and operatively connected to said diaphragm, and means engaging said stylus carrier substantially in the plane of said flat surface, for holding said stylus carrier in said notch. v

6. In a phonographio sound box, the con;-

5 bination of a casing having a notch or depression in the periphery thereof, a diaphragm in said casing and a stylus carrier operatively connected to said diaphragm,

and having a flat surface foiengagement with the Walls of said notch, said surface having a cu'rvededge Signed at New York city, New York, this 27th day of June, 1918. V e

JOSEPH HOFFAY. 

